The present invention relates to a negative pressure relief valve for use in the intake tract of an I.C. engine. More specifically, the invention is a valve adapted for use in an I.C. engine intake tract that uses a pressure relief structure activated in response to excessive negative pressure (vacuum) within the intake tract.
In the field of I.C. engines adapted for use in various applications, the air source for the engine is often displaced from the intake plenum of the engine. In an automobile, for example, the air intake source is often placed in an area remote from the intake plenum. The locations used by various automobile manufacturers have included shrouds behind headlamps, air scoops located on external surfaces of the vehicle, inner fender-well shrouds, and hot air intake shrouds positioned near, and heated by, exhaust gas manifolds. In applications of I.C. engine use in generators, air compressors, and pumps, the air intake is often located near an external surface of the surrounding cover of the machine. In truck, agricultural, military, and other overland (off-road) applications of I.C. engine use, the air intake can be extremely remote from the intake plenum of the engine. An example of extreme remoteness is in a military vehicle adapted for crossing bodies of water in a partially submerged condition. In such instances, the intake tract can be several feet in length and extend to the roofline of the vehicle.
The design objective of any air intake for I.C. engine use is to create a reasonably reliable source of uncontaminated air for consumption by the engine during normal operation. Virtually all intake systems additionally include a filtering system for the air that can be an oil bath type, paper filter, treated filament filter, foam, mesh type, etc., positioned between the air intake and the actual intake plenum of the engine.
In any of the foregoing intake systems, the possibility occurs where the outside air intake of the intake tract can become fouled with water or other obstruction. If the water or other obstruction is passed through the intake tract to the intake plenum and ultimately into the I.C. engine, severe operational impairment or total failure of the I.C. engine can result. This possibility can occur, for example, where an I.C. engine is used in an automotive application and the automobile is used to pass through deeper water than anticipated by the manufacturer of the vehicle. The air intake may be overtaken by a wave of water created by the vehicle movement and water passed into the intake tract and into the engine resulting in failure. In another example, an I.C. engine equipped pump, generator, or compressor may be used in a location that causes the air intake to become submerged, even momentarily, resulting in failure of the engine.
The present invention is directed to solving the problem of water, or other obstruction, unintentionally infiltrating the intake tract of an I.C. engine. The invention is a negative pressure relief valve positioned along the intake tract of an I.C. engine. When the intake tract experiences a sufficient pressure differential between ambient pressure and the negative pressure developing within the intake tract, the valve opens and allows air to pass directly into the intake tract from a second source. The second source of air can be the air located within the surrounding engine cover associated with the I.C. engine, or may be air from a second source also remote from the immediate proximity of the I.C. engine.
In one embodiment of the invention, the valve is adapted to substantially surround the intake bore of the intake tract. The valve includes a multi-ported or vented structure that rings the intake tract and is valved by a proximate resilient multi-diaphragmed structure mated thereto in correspondence to the multiple ports. The resilience of the diaphragm is selected according to a predetermined pressure differential level for activation of the valve. For example, a large displacement I.C. engine truck or military application of the valve would require a relatively high resilience for the diaphragm whereas a smaller displacement motorcycle or pump I.C. engine would use a diaphragm of a relatively lower resilience. To supplement the natural resilience of the diaphragm, a foam spring, for example, can also be positioned to support the diaphragm.
These and other features of the invention will become apparent from the following detailed description, claims, and drawings herewith. The various features may be implemented in whole or part without departing from the spirit and scope of the invention. The valve, for example, may be used in any negative pressure (vacuum) air tract where a certain threshold of negative pressure is not to be exceeded. Examples would include any air tract where collapse of the tract, over-heating of the vacuum source (i.e., pump), or other potential failure might result owing to excessive negative pressure occurring as a result of blockage of the tract.